I see an official answer from @staff to 7768 that it doesn’t secure images by design since the “private” blogs feature is actually meant as a “temporary” or “coming soon” blog feature.
I am tens of hours deep with Ghost now and just found out it won’t work for my private photoblog. By any chance has there been a change of heart at Ghost in the last to make this feature actually mean “private”? If not, I would request clearer documentation. I strongly believe the current documentation is misleading about a sensitive topic. Ghost advertises strongly on being secure and easy for non-technical users. This is a very serious gap that I imagine has trapped a lot of people (many of whom may not realize their photos are in danger!).